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(No Model.)

E; HOFINGHO'FP.

PIANO PORTE.

No. 353,453. Patented Nov. 30,1886.

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UNITED STATES PATENT OFFICE.

EMIL HFINGI-IOFF, OF BARMEN, PRUSSIA, GERMANY.

PIANO-FORTE.

`,SPECIFICATION forming part of Letters Patent No. 353,453, dated November 30,1886.

Application lcd January 30, 1836. Serial No. 190,306. (No model.) Patented in Germany June 5, 1885, No. 33,779. and in England June 5, 1885, No. 6,850.

To all whom it may concern:

Be it known that I, EMILHFINGHOFF, merchant, oll the town ol' Barmen, Rhenish Prussia, German Empire, have invented a new and useful Improvement in Pian o-Fortes, (for which I have obtained patents in Germany, bearing date June 5, 1885, No. 33,779, and in Great Britain, bearing date June 5, 1885, No. 6,850,) of which the following is a full,clear,and exact description.

My invention relates to improvements in the tone or sound and to the conservation ofpianoside and partially in section.

fortes, and is intended to give the following results: First, by my improvements the power of tone or sound ot'apianoforte (grand piano) can be diminished to a minimum at the will ofthe player; second, the tone will be improved in quality; third, the piano, and especially the sounding-board, will be guarded against the ruinous iniluences of temperature and dampness,and consequently an instrumentprovided with my improvement will have a sound of good quality much longer than without my improvement. These objects are obtained by the arrangement illustrated in the accompanying drawings, in which- Figure l is a vertical view ol the piano, showing that part relating to my invention in section, and arranged for opening the sounddamper by hand. Fig. 2 is a vertical View of a piano, showing that part relating to my invention in vertical section, but arranged for opening and closing by a pedal and a counterbalancing device. Fig. 3 is a back view of a piano with my sound-daniper, seen partially i'rom the outside and partially from the inner Fig. 4 is a horizontal section of Fig. 2 through line I II.

My invention consists in a damper-cover,B, which is fastened to the back of the piano, or to the bottom of the grand piano. This cover is hinged to the instrument by the hinges C, so that it can be opened or closed conveniently. As shown by Figs.1 and 3, (left side,) the cover is held tight by the cramps or hooks D, and it must be opened or closed by hand. It can be iiXed to any desirable amount of opening by any convenient device.

The arrangement shown in Figs. 2 and 3 (right side) represents my damper-cover in connection ywith a pedal, M, to which it is joined by a rack, O, and part of atooth'cd pinion, N. By this means the damper-cover can be opened or closed at pleasure by the player, while playing,siinply by pressing with his foot more or less on the pedal. In order to make this as easy as possible, and also to counterbalance the weight of the cover in every position,of Which,as will be understood, the downward pressure will be the greater the more the angle of opening increases, the rack N is attached to a rod, P,with a sort of a piston-head, which enters into a tube or case, R, in which is inclosed a spiral spring, S, against which the piston-top ofr the aforementioned rod P presses. It follows from this device that the more the damper-cover is opened the greater will be the counter-pressure of the spring on the top of the rod P, and so both can be held perfectly in equilibrium in any position, and hardly any strain will be required to be exerted by the player with his foot on the pedal to open the damper-cover to any degree, and ifthe spring S is made a little stronger than the counteraction of .the gravity of the open cover the latter will always close automatically.

the damper-cover in any position-might be obtained by other mechanical arrangementssuch as, for instance, a cord running round a little pulley and a counter-weight attached to the free end of the cord, or, better, by a cord ruiming round a grooved `pulley having a volute shape, and such like mechanisms.

The cover B is provided at the inner sidethat is, the side facing the sounding-boardwith wood boxes or dampers A, which take nearly up the spaces between the frame E of the instrument at the back side of the piano, or at the bottom of a grand piano, when the cover is closed, ornearly so. These boxes are iilled out with cotton-waste or other suitable material which is abad conductor of sound, orhas the quality of damping the sound.

The device used until now in closing the backs of piano-fortes by alight frame containing a panel of wire-gauze or another light woven stuff has the great disadvantage that dam pness and other influences of temperature are in no way hindered from having a destructive effect to the sounding-board, and so Of course the same result-4J. e., balancing gradually ruining its resounding quality or its vibratory power. The inner mechanism also-the strings, &c.-suffers by dampness entering the instrument by the open back. This is obviated by the dampercover described, which locks up the sounding-board almost airtight, and an instrument can be kept in use much longei` than before.

I am aware that a soundingboard on which a piano was placed has been provided with a pedal-operated damper-board having a fabriccovered face.

I am also aware that the rear part ofa pianocover has been hinged, so that it can also be raised to operate somewhat after the manner of a swell-shutter; and I do not elaimthe same as of my invention.

I claim as my inventionl. The combination, with a pianoforte, of a hinged cover for the space behind or under the sound-board,the said coverhaving a. filling of fibrous or analogous sound-deadening ma.- terial, substantially as set forth.

2. The combination, with a piano-forte, of

a cover hinged to open or close the space behind or below the sonnd-board, a damperbox projectinginto the sound-box from the inner face ofthe cover,and a fibrous or analogous sound-deadening filling in the said damper box, substantially as set forth.

3. The combination, with a pianoforte having the frame E, ofthe cover B,having the spaced damper-boxes A on its inner face entering the sound-chamber,and havinga fibrous lling, the toothed segment N,connected with the cover, the rack O.y meshing with the segment, the rod I?, connected to the rack, the spring S,acting against the rod, and the lever or treadle M, pivoted to the frame and to the rod P, substantially as set forth.

The foregoing specification of my improve ment in piano-fortes signed by me this 16th day of December, 1885.

MIL HFINGHOFF.

Witnesses:

GEO. Koen, CARL UFER. 

